title: Chiral Lewis acid catalyzed asymmetric cycloadditions of carbonyl ylides generated from diazoimide derivatives and their synthetic applications to indolizidine alkaloids.
abstract: Highly enantioselective 1,3-dipolar cycloaddition reactions, catalyzed by chiral Lewis acids, between several 3-(2-alkenoyl)-2-oxazolidinones and carbonyl ylides that were generated from N-diazoacetyl lactams are described. Reactions of N-diazoacetyl lactams that possess 5-, 6-, and 7-membered rings were transformed to the corresponding epoxy-bridged indolizidines, quinolizidines, and 1-azabicyclo[5.4.0]undecanes with good to high enantioselectivities. Regio- and stereoselective ring-opening of the epoxy-bridged indolizidine cycloadduct gave the corresponding alcohol as a single diastereomer. The sequence of asymmetric cycloaddition followed by ring-opening was applied to the syntheses of several chiral indolizidine derivatives, including (+)-tashiromine.
authors.affiliation: Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University , Wakasato, Nagano, Nagano Prefecture 380-8553, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suga
authors.forename: Yuta
authors.initials: Y
authors.lastname: Hashimoto
authors.forename: Shingo
authors.initials: S
authors.lastname: Yasumura
authors.forename: Ryota
authors.initials: R
authors.lastname: Takezawa
authors.forename: Kennosuke
authors.initials: K
authors.lastname: Itoh
authors.forename: Akikazu
authors.initials: A
authors.lastname: Kakehi